jQuery Simple Example

HTML

<script src="//www.addressfinder.co.nz/assets/v2/widget.js"></script>
<form>
  <label>Checkbox 1 <input type="checkbox"></label>
  <label>Checkbox 2 <input type="checkbox" checked></label>
  <label>Checkbox 3 <input type="checkbox"></label>
  <label>Checkbox 4 <input type="checkbox" checked></label>
</form>

<button>
  Uncheck all
</button>

JavaScript

$(document).ready(function() {
  $("button").click(function(){  
    $('input[type="checkbox"]').prop('checked', false);
  });
});